The invention relates to a structural HCMV phosphoprotein of 28 kD (pp28) and immunogenic parts thereof, to the preparation thereof by genetic manipulation, and to the use thereof as a diagnostic aid and for producing antibodies and vaccines.
To date, HCMV polypeptides with molecular weights of about 28 kD have been described in several investigations. Roby and Gibson (Roby, C. and Gibson, W. (1986) J. Virol. 59, 714-727) and Nowak et al. (Nowak, B. et al. (1984) Virology 132, 325-338) describe a phosphoprotein of about 24 kD and 29 kD, respectively. It is suggested in both publications that this protein is localized in the matrix. Pereira et al. (Pereira, L. et al. (1984) Virology 139, 73-86) describe a monoclonal antibody which precipitates from infected cell extracts a 25 kD glycoprotein which belongs to the glycoprotein D complex. Irmiere and Gibson (Irmiere, A. and Gibson, W. (1985) J. Virol. 56, 277-283) have identified a 28 kD protein which was found both in the A and in the B capsid of various HCMV strains. Re et al. (Re, M.C. et al. (1985) J. Gen. Virol. 66, 2507-2511) investigated a 28 kD structural protein using a monoclonal antibody P2G11 (MAb P2G11). It remains unclear whether this was the protein described by Pereira et al. (loc. cit.) or that described by Nowak et al. (loc. cit.).
Since a structural protein of 28 kD is recognised by almost all highly positive human sera, and thus the 28 kD proteins must include one of the principal immunogens of HCMV, it appears desirable to identify and to isolate the HCMV gene coding for it. Another aim was subsequently to express this gene in suitable host systems in order to characterize it more accurately and, possibly, to establish it as another principal immunogen of HCMV.
It has been found that it is possible with the MAb P2G11 (Re et al. loc. cit.) to identify and isolate from an HCMV cDNA gene bank clones which code for a 28 kD phosphoprotein (pp28). To date no phosphoprotein 28 kD in size has been disclosed.